Antipersonnel fragmentation weapon

ABSTRACT

1. In an explosive fragmentation assembly, a length of explosive cord having airborne suspension means at one end and an impact fuze at the other end, a plurality of inverted frustoconical pellets secured in spaced relation on and along said cord in progressively decreasing intervals from said impact fuze to said airborne suspension means, each said frustoconical pellet having a side surface formed at a predetermined angle, and a frustoconical casing snugly embracing the side surface of said frustoconical pellet and having a series of grooves in its surface defining fragments to be projected in a line substantially normal to the side surface of said frustoconical pellet on detonation of said impact fuze.

United States Patent Primary Examiner-Samuel W. Engle Attorneys-W. E. Thibodeau and T. J. Lynch CLAIM: 1. In an explosive fragmentation assembly, a length of explosive cord having airborne suspension means at one end and an impact fuze at the other end, a plurality of inverted frustoconical pellets secured in spaced relation on and along said cord in progressively decreasing intervals from said impact fuze to said airborne suspension means, each said frustoconical pellet having a side surface formed at a predetermined angle, and a frustoconical casing snugly embracing the side surface of said frustoconical pellet and having a series of grooves in its surface defining fragments to be projected in a line substantially normal to the side surface of said frustoconical pellet on detonation of said impact fuze.

PATENTEDnm 19 Ian m a 2 m M 6 9 l W W H C Ag I a M Mu M AN TIPERSONNEL FRAGMENTATION WEAPON The invention described herein may be manufactured and used by or for the Government for governmental purposes, without the payment to me of any royalty thereon.

This invention relates to a high-explosive antipersonnel weapon in which a large area of lethality per pound of weapon is effected. It is known that a dispersal of many small high-explosive bombs will theoretically produce a far greater lethal area than a single bomb of the same total weight. However, it has been heretofore difficult or impossible to realize this theoretical advantage, because of the necessity of equipping each small bomb with a fuze whose necessary safety features and operating mechanism occupied a substantial fraction of the weight of such small bombs.

The present invention overcomes this difficulty by providing a novel array of explosive units each of which is explosively linked with and spaced from the others by a flexible detonating cord (one commercial brand is widely known as Primacord") so as to form a single explosive system capable of being detonated by a single fuze which constitutes a small fraction of the total weight of the system. This combination comprising many small explosive filled units in spaced relation along a flexible detonating cord, together with a single detonating fuze at one end of this cord, thus makes possible a greatly improved lethal efficiency while at the same time assuring a uniform dispersal of fragments over the target area.

One object of the invention is to provide a high-explosive fragmentation antipersonnel weapon in which control of the extent of the target area and the density of the fragments striking a given area is accomplished by progressively lessening the spacing of the explosive units on the detonating cord.

Another object of the invention is to provide an antipersonnel weapon which is suspended by a parachute for substantially vertical downward flight on a line parallel with the iongitudinal axis of its detonating cord to cause great dispersal of fragments of the units. A further object of the invention is to provide streamlined explosive units to reduce aerodynamic drags during the vertical descent of the assembly and which will also lessen the effect of cross winds.

Other objects and advantages will be apparent from the following detailed description and the accompanying drawings, in which:

FIG. 1 is a diagrammatic view of one form of the invention,

FIG. 2 is longitudinal sectional view with parts in elevation, of a portion of FIG. 1 showing a preferred contact fuze,

FIG. 3 is a sectional view of a slightly modified form of explosive unit, and

FIG. 4 is an elevational view, partly in section of a further modification of the explosive unit.

Referring now to FIGS. 1 and 2 of the drawings it will be seen that a detonating cord C of predetermined length carries the various elements of the assembly and is in turn secured at its upper end to the lines 8 of a parachute 7 for linear descent toward the ground surface. The detonating cord C comprises a sheath 1 containing a high-explosive tiller 2. At intervals, to be hereinafter more fully disclosed, a series of explosive units B are strung along and surrounding the cord C. Each unit includes a preformed pellet 3 of an explosive composition, such as compacted tetryl, having its lower end of inverted frustoconical form. A frustoconical metal casing 4 having fragmentation grooves stamped therein is secured to the lower frustoconical face of the pellet 3. The pellet 3 extends upwardly beyond the metal casing 4 in upright frustoconical form to reduce horizontal wind resistance during descent of the assembly. The units B are spaced at progressively shorter distances apart upwardly to assure a homogeneous density of fragments striking the ground area within the range of the weapon when the fuze is detonated.

FIG. 3 discloses a modified form of unit B in which the explosive pellet 3 and its frustoconical casing 4 are similar to the unit disclosed in FIGS. 1 and 2, but having an added cover 22 to deflect the pressure of the expanding gases away from the adjacent upper unit when the units are closely positioned on the detonator cord C.

A second modified form of fragmentation unit Be is threaded along a detonator cord C, as shown in FIG. 4, and has an explosive filler 2' of spherical shape surrounded by a hollow spherical casing 4 having fragmentation grooves 5'. Either form of the fragmentation units, shown in FIGS. 3' and 4, may be used with a horizontally suspended length of detonator cord and a trip fuze (not shown) operating in response to tension. When the invention is used in the abovedescribed form, the units B and Ba are equally spaced on the detonator cord. The point detonating contact fuze shown in FIG. 2 consists of a streamlined metal body 6 into which the detonating cord C enters axially at the top and to whichcord C is secured by crimping or cementing. Slideably mounted in the axial cavity of fuze body 6 is a plunger 10 carrying within it the detonator 9. Plunger 10 is retained within-body 6 by pin 17 acting in groove 18 formed in plunger 10. The firing pin 13 is fonned integrally with striker piston 11, which in turn is slideably mounted in an axial hole in plunger 10 and retained therein by pin 15 acting in striker piston groove 16. A safety pin 12 passes through fuze body 6 and plunger lfl, and intervenes between detonator 9 and firing pin 13.

When pin 12 is withdrawn striker piston 11 is prevented from motion relative to plunger 10 and detonator 9 by the ball 14 which reposes in a radial hole in plunger 10. The assembly 10-11 is thus held in a forward position only by creep spring 20.

On impact, the assembly 10-11 is forced inward until the detonator 9 is brought into armed proximity with the end of detonating cord 1. Simultaneously the foregoing displacement brings ball 14 opposite the release groove 19 thereby permitting relative motion between striker I1 and plunger 10.

The operation of the invention is made more apparent by the following. It is an observed phenomenon that metal fragments lying on the surface of an explosive body leave this body very closely, on the average, in a direction normal to this surface. Consequently, the fragments of these frustoconical'casings will spray out from this geometry of pellet in a conical annulus directed downward at the 0 angle, FIG. 1, which the normal to the surface of pellets 3 and casings 4 makes with the horizontal. This is confirmed by experiment.

The present invention provides a novel form of spaced, explosively linked, miniature fragmentation bombs that may be delivered to the target by air, rocket or shell, or may be suspended above the ground by stakes to be detonated by a trip fuze, or laid on the ground in the form of a mine or booby trap. The embodiment of the invention of FIGS. 1 and 2 disclosing a series of frustoconical fragmentation casings strung along detonating cord C is more adaptable against ground targets when delivered by air since the detonating cord is in an approximately vertical position at detonation. Under thesecircumstances, the frustoconical casings project all their fragments downward onto the target area of the ground, so that no fragments are lost by moving away from the target. This concentration of the direction of projection of the fragments by this geometry thereby further improves the lethality per pound of the weapon. The spacing of such frustoconical explosive filled units on the detonating cord may be chosen so as to give a statistically homogenious density of fragments over the target area. The aerodynamic drags of such frustoconical explosive units on their detonating cord cause the system to fly stably with the axis of the detonating cord substantially vertical. To assist this type of flight, the preferred embodiment discloses a drag member such as the parachute 7 attached to one end of the weapon.

On descending contact, the firing pin 13 under the continuing force of impact strikes the detonator 9 thereby detonating the detonator cord C and with it all the explosive pellets 3. The fuze action holds the fuze in a detonator safe condition until the moment of impact, at which time it simultaneously arms and fires the fuze by the foregoing mechanism.

It is generally required in antipersonnel weapons that a relatively uniform density of fragments per unit area of target be delivered. If this density is designated K, this invention teaches that the distance d between each pair of successive frustoconical fragment casings 4 each having n preformed fragments will be where is the angle between the normal to the axis of the detonating cord and the normal to the frustoconical fragment surface of 4, and s is the distance from the fuze body 6 to the lower of the said pair. Equation (1) is derived from the relation K=nl2rrRr s=R tan 0, and e r tan 6 as shown in the geometry of FIG. 1.

Any uniform system of units applies to equation 1 Thus, a weapon of the type disclosed in FIGS. 1 and 2 constructed in accordance with equation (1) will, when detonated vertically, produce a uniform fragment density on a flat target area.

The parachute 7 secured to cord C by lines 8 is provided to enhance the natural tendency of the cord and its units to fall with its axis vertical.

It will thus be seen that I have provided a weapon which will project a shower of lethal fragments uniformly and effectively over a target area which is only limited by the length of the detonator cord. The upper units are spaced at progressively shorter distances apart to insure distribution of a greater number of fragments in the progressively larger circumferential target areas to be covered by each unit. The present weapon discharges its fragments in a downward angular direction to the ground surface and is more effective than weapons discharging fragments upwardly or horizontally.

While I have disclosed a form of the invention presently preferred by me, various changes and modifications will occur to those skilled in the art after a study of the present disclosure. Hence the disclosure is to be taken in an illustrative rather than a limiting sense; and it is my desire and intention to reserve all modifications falling within the scope of the subjoined claims.

Having now fully disclosed the invention, what I claim and desire to secure by Letters Patent is:

1. In an explosive fragmentation assembly, a length of explosive cord having airborne suspension means at one end and an impact fuze at the other end, a plurality of inverted frustoconical pellets secured in spaced relation on and along said cord in progressively decreasing intervals from said impact fuze to said airborn suspension means, each said frustoconical pellet having a side surface formed at a predetermined angle, and a frustoconical casing snugly embracing the side surface of said frustoconical pellet and having a series of grooves in its surface defining fragments to be projected in a line substantially normal to the side surface of said frustoconical pellet on detonation of said impact fuze.

2. In an explosive fragmentation assembly, a length of explosive cord having airborne suspension means at one end and an impact fuze at the other end, a plurality of inverted frustoconical units secured in spaced relation on and along said cord in progressively decreasing intervals from said impact fuze to said airborne suspension means, each said unit comprising a frustoconical casing scored in its surface for fragmentation, and an explosive charge within said casing and extending beyond in upright frustoconical form, said adjacent and opposite frustoconical forms reducing wind resistance in both vertical and horizontal directions.

3. In an explosive fragmentation assembly, a length of explosive cord, an airborne suspension means attached to one end of said cord, an impact fuze attached to the other end of said cord in detonating relation with said cord, and a series of explosive units secured on said cord in progressively decreasing interval from said impact fuze to said airborne means, each of said units comprising a preformed pellet of explosive composition, its lower portion defining an inverted frustoconical form and a casing, having fragmentation grooves on its outer peripheral surface, surrounding said lower portion, the remaining portion of said pellet above said casing defining an upright frustoconical form.

4. In an explosive fragmentatlon assembly, a length of explosive cord, and a plurality of explosive units secured in spaced relation on and along said cord, said length of cord having airborne suspension means at one end, and an impact fuze at the other, the spacing of said units decreasing progressively with increase in distance from said impact fuze to said airborne suspension means, each said unit comprising a generally frustoconical metallic casing weakened along lines defining a predetermined plurality of fragments, and a body of explosive within said casing. 

1. In an explosive fragmentation assembly, a length of explosive cord having airborne suspension means at one end and an impact fuze at the other end, a plurality of inverted frustoconical pellets secured in spaced relation on and along said cord in progressively decreasing intervals from said impact fuze to said airborn suspension means, each said frustoconical pellet having a side surface formed at a predetermined angle, and a frustoconical casing snugly embracing the side surface of said frustoconical pellet and having a series of grooves in its surface defining fragments to be projected in a line substantially normal to the side surface of said frustoconical pellet on detonation of said impact fuze.
 2. In an explosive fragmentation assembly, a length of explosive cord having airborne suspension means at one end and an impact fuze at the other end, a plurality of inverted frustoconical units secured in spaced relation on and along said cord in progressively decreasing intervals from said impact fuze to said airborne suspension means, each said unit comprising a frustoconical casing scored in its surface for fragmentation, and an explosive charge within said casing and extending beyond in upright frustoconical form, said adjacent and opposite frustoconical forms reducing wind resistance in both vertical and horizontal directions.
 3. In an explosive fragmentation assembly, a length of explosive cord, an airborne suspension means attached to one end of said cord, an impact fuze attached to the other end of said cord in detonating relation with said cord, and a series of explosive units secured on said cord in progressively decreasing interval from said impact fuze to said airborne means, each of said units comprising a preformed pellet of explosive composition, its lower portion defining an inverted frustoconical form and a casing, having fragmentation grooves on its outer peripheral surface, surrounding said lower portion, the remaining portion of said pellet above said casing defining an upright frustoconical form.
 4. In an explosive fragmentation assembly, a length of explosive cord, and a plurality of explosive units secured in spaced relation on and along said cord, said length of cord having airborne suspension means at one end, and an impact fuze at the other, the spacing of said units decreasing progressively with increase in distance from said impact fuze to said airborne suspension means, each said unit comprising a generally frustoconical metallic casing weakened along lines defining a predetermined plurality of fragments, and a body of explosive within said casing. 